Many furniture products, including such products as chairs, sofas and automobile seats utilize sinuous wire spring elements as to create resilient surfaces, such as seats and backrests, in an item of furniture. Such resilient spring elements are disclosed, for example, in U.S. Pat. No. 2,800,928. Generally, these spring elements are of an arcuate or curvilinear shape which creates a problem in storing and using those elements, particularly if those elements are manufactured in one facility and utilized in another manufacturing facility. It has therefore become common practice to create a nested bundle of those elements for storage or shipment from one location to another.
U.S. Pat. No. 4,270,582 discloses a machine for creating a nested bundle of such arcuate configurated sinuous springs. According to the disclosure of this patent, precut straight spring elements are fed into the machine which imparts an arcuate curvilinear shape to the spring elements. The curvilinear or arcuate spring elements are engaged by the teeth of a gear or protrusions on the surface of a feed wheel to feed or load those curvilinear or arcuate-shaped sinuous spring elements into a first or primary cage or drum which effectively compresses the arcuate spring element into a generally circular configuration within the interior of the primary cage or drum. After the completion of the loading of the arcuate spring into the interior of the primary cage or drum, a stripper is actuated to impart an axial force upon the compressed circular-shaped arcuate spring, causing it to pass into a secondary cage or drum of larger diameter where the arcuate spring expands into contact with the interior surface of the secondary cage or into contact with the interior surface of a previously loaded arcuate spring contained within the secondary cage. After a predetermined number of springs have been loaded into the secondary cage or drum, the secondary drum is rotated to an unloading position whereat a stack of nested arcuate spring elements are removed from the secondary cage.
U.S. Pat. No. 5,150,600 also discloses a machine for automatically creating nested stacks of arcuately configured sinuous springs similar to the disclosure of U.S. Pat. No. 4,270,582. This patent also inserts the arcuately configured springs into the interior of a primary or first cage or drum so as to create a generally circular configured arcuate spring and then passes that generally circular arcuate spring from the interior of the first primary drum into the interior of a larger diameter circular cage or drum whereat the generally circular configured arcuate spring expands into contact with the interior surface of the secondary cage or drum or into contact with a previously inserted circular configured arcuate spring. According to the disclosure of this patent, a stripper is actuated after a predetermined number of sinuous springs have been nested within the interior of the secondary cage or drum so as to deposit the stack of nested springs onto a discharge chute.
Machines made in accordance with the disclosure of the above-identified patents are subject to the criticism that they are generally very noisy because of the clash of the input feed wheels with the transverse parallel bars of the sinuous springs. They are also subject to the criticism that they are very limited in the configuration of the springs which they are able to handle without a substantial reset-up and reconfiguration of the machines, often times requiring many hours or even days of reset-up operator time. The nature of sinuous springs, though, as used in the furniture industry, is that there are hundreds or even thousands of different furniture products which utilize such springs of varying and differing length, resilient characteristics, temper of the spring wire, differing gauge wire and spacing of the parallel bars of the spring. All of these differing characteristics of the sinuous springs dictate that a machine for nesting such springs should be capable of handling and stacking sinuous springs of varying dimensions and characteristics. It has therefore been an objective of this invention to overcome these limitations relative to the versatility of the machine to handle arcuate springs of different lengths and configurations with minimal requirements for reset-up operator time.
Another objective of the invention of this invention has been to increase the speeds of the machine and maintaining continuity of springs in a stack of nested springs created by the machine. The nature of sinuous springs is that if the sinuous springs being stacked by the machine have an uneven number of bars in the individual spring element, every other spring in the stack will have an end section which is curved in a direction opposite to the end of the spring which preceded it. It has therefore been an objective of this invention to create stacks of nested coil springs of either even or uneven number of parallel bars in which all of the end turns of the stack of springs in a nest are oriented in the same direction. At the present time, there are no machines, including the machines described in the above-identified patents, capable of nesting and stacking sinuous wire springs having uneven numbers of parallel bars with the end turns of the springs oriented in the same or a common direction as required by furniture manufacturers. Such uneven number of bar sinuous springs, which are commonly used in the furniture industry, are now manually removed from the machine which imparts an arcuate configuration to the spring and manually stacked in a nested arrangement.